Heat-treated nickel-copper-aluminum alloy and method of heat treating the same



Patented Apr. 22, 1930 i UNITED STATES PATENT OFFICE "WILLIAM A. MUDGE, or HUNTINGTON, wEsrvraerm, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO THE IN'1.ERNA'J.ION'AL NICKEL COMPANY,

1110., on NEW 2031:, n. Y., A CORPORATION or DELAWARE HEAT-TREATED moKEL-ooPrEE-ALUmmom ALLOY AND METHOD OF HEAT TREATING alloys containing as their main ingredients any following discoveries 'ness will be increased, while the elongation product, even when of constant composition,

THE SAME No Drawing. application filed June 10, 1924. Serial No. 719,088.

My invention relates to the treatment of the rate of cooling, but slow cooling from of the temperatures above mentioned nickel, copper and aluminum, and it may be will, in general, give better physical properapplied to any ternary alloy containin these ties than when the material is rapidly cooled three metals as its major ingredients, w the aluminum content is preferably not over 20%. i

In the manufacture of such alloys, a wide variation in the physical properties of the other suitable q uenching medium.

If the material is heated to atemperature above 1200 F., there will be a decreasein has been observed, and no reason could be will be proportional to the increase in te assigned for such variations, inasmuch as the perature from 1200 F. up to below 1800 F. alloy was supposed to be a true solid solution. Also the rate of cooling will affect the de- I have discovered that this alloy is not a. sired physical properties in this case. When true solid solution and that the physical rapidly-cooled or quenched, the desired prop- 65' properties of a constant composition thereof erties will be slightly lower than when slowmay be changed to a considerable degree by ly cooled from the sametemperatures.

heat treatment. I believethis to be due to Also, there is a time effect in the heating, the formation, during heating above 500- since extending the time of heatingtends to erein from these'same temperatures, as for example, by quenching 1n oil or water orin any these physical properties, and this decrease 600 F., of a compound-between two of the increase thedesired physical properties. For

constituents, namely, copper and aluminum. examplegusing dead soft material and one, I have found that the amount of this comhours heating at the best temperature of pound, even in a constant composition of alabout 1100 F, would give sem -hard mateloy, varies in accordance with the heat treatrial, whether cooled slowly or rapidly; wherement, and, therefore, I believe that it gives as, 1f this heating at this same temperature on.

the variation in physical characteristics. The the same material was continued for eight or amount of this compound will also vary with more hours, a hard material will be produced different compositions, even under the same having physical properties considerably in heat treatment. excess of those produced in one hours heat In a long series of experiments on heat treatment; and this again, treatment of this material, I have made the ing is rapid or-slow.

Continued heating If the material has been quenched from a perature of about 1100 temperature above 1500 F., it will be dead eight h S will Slightly,

at the maximum tem- F. for more than but definitely, in-

soft. If such dead soft material is heated, I- crease the physical properties regardless of have found the following facts: the rate of cooling.

. ((1) Up to about 600 F., there will be praci As specific illustrations of these treatments, tically no change in the physical properties. I will recite the following examples, the ma- (b) Between 600 F. and 1000 F., a gradterial treated being composed of approx ual increase in desirable physical properties" mately 66% nickel, 26% copper, 4% aluml- 90 and hardness will result; and num, together with 4% won and manganese (0) At a range from 1000 F. to 1200 F., and .19% of carbon as minor constituents. themaximum desired properties will be de- 1st ewampZe.-Or1g1nal material whose veloped. I proportional limit was 92,000 lbs. ps1. was

By physical properties in the above statequenched from 1500 E, which reduced its 95 value to 25,000 lbs. psi. Heating at 1100 F. v raised;the proportional limit from its original 25,000 lbs. psi, up to 70,000 lbs. psi. during the first hour. was raised to 94,000 lbs. psi. at the end of the ment', I meanv that the proportional limit, yleld point, and ultimate strength and hard-' and reduction of area will be decreased. 'Iheabove statements apply regardless of ,1 The proportional limit whether the coolseventh hour and to 97,000 lbs. psi. at the end of the forty-eighth hour. In this case, all the Similar results to those above recited have been obtained with a composition containing of nickel, of copper, 4% of aluminum, together with 1.5% of iron and manganese and 06% carbon as minor constituents.

2nd cmampZa-When this alloy has been hardened and the desired physical properties developed to a high value by the heat treatment, such as before described, it may be heated in the following ways without alfecting its properties: y

-(a) To any temperature not to exceed 1300 F. with slow cooling (b) To any temperature not exceeding 1200 F. with quenching or quick cooling.

This discovery is important, especially in using the material in locations where it is subjected to variations in temperaturecondi-' tions; as, for example, when used for steam turbine blades. The maximum temperature in turbine work is lower than the above points, and hence, the material will retainits desired physical properties under these conditions, even under wide variations of temperature.

In other words, intermittentservice ator be-' low-these temperatures does not materiallychange the .characteristics of the material, if

tested when cooled down.

If the material is heated above these temperatures, a decrease in the desired physical properties will result, without regard to the rate of cooling; but if the material is slowly cooled after such heating, it will have higher properties than if quenched after heating to above such temperatures.

3rd ewampZa-Jf this hardened material is heated to a point between 1200 and 1500 F, a semi-hard material will be produced, regardless of the rate of cooling; although the slowly cooled material in this case will be slightly harder than the quenched or rapidly cooled material. If this hardened material is heated to above 1500 F., and quenched or rapidly cooled, it will produce dead soft material; while slowly cooling it from a temperature of 1500 F. or above, will produce a semi-hard material.

The above examplesrecite the maj'or disscribe certain other features which I have found in this research.

Either the dead soft or semi-hard alloy, when these properties have been imparted by the proper heat treatments, can be machined or fabricated with about the same ease as a similarnickel-copper alloy containing no aluminum.

If the materiafis hardened and has the do sired physical properties to a high degree, it L is machined with considerable difliculty. Therefore,-anyone machining or fabricating this material while relatively cold and without material heating. to obtain a certain article or device, would probably desire it in soft or semi-hard condition for such treatment; and thereafter the desired physical properties can be imparted by heating at from 1000 F. to 1200 F., the properties increas-.

ing with the length of heating,'as above described, and being preferably followed by a slow cooling to bring these properties to their highest values.

Where the material is worked in hot condition for sale in merchant shapes, the best practice would probably be to roll or forge it at a temperature between 1800 F. and about 2150 F, with ordinary slow cooling in the air. This will give a semi-hard product, without any further treatment, and if the customer desired a dead soft material, the material as rolled or otherwise hot worked should be quenched or quickly cooled from a temperature above 1500 F. to give a soft ma terial.

If, on the other hand, a customer desired a very hard alloy, possessing the desired physical properties to a high degree, the best practice would beto allow the material to cool slowly after hot working at the above temperatures, and then to heat the material at from 1000 to 1200 F for several hours and allow it to cool. slowly inthe air. As above pointed out. the longer this heating extends within-certain limits, the more of the compound will be formed and the greater the physical characteristics.

My belief is that the hardness and other desired physical properties are due to the gradual formation of the copper-aluminum compound during-the heating at a temperature between 1000 F. and 1200 F.

I have also found that where the desired properties are imparted, either to a high degree or to a medium degree. these properties are slightly improved by aging the material. Thus, where the material has been quenched from above 1500 F. to produce dead soft material, the proportional limit being reduced from 92,000 lbs. psi. to 25,000 lbs. psi.. rthis material was'heated at about 1100 F. for two hours. and some samples q enched and others slowly cooled. coveries whlch I have made in my heat treat 1 ment research on such alloys. I will now de- In both cases one'sample was tested about five minutes after cooling and another about 19 hours after cooling. The aged samples from both the quenching and the slow cooling were found tobe improved in proportional limit, by from to 5 The advantages of my invention will be apparent to those skilled in the art, since the heat-treating of this alloyfn accordance with the above discoveries, enables its properties to ,be varied as desired, and definite and uni- 10 form results obtained-in the desired physical properties of the alloy and in accordance with the characteristics desired.

The relative proportions of the alloy may be varied, thepercentages of other ingredi aluminunr and at least-15% of nickel, the steps consisting of heating the material and subjecting it to a regulated coolin action, the heating and cooling being su cient to change the physical properties.

3. In the treatment of nickel-copperaluminnm alloy containing less than 20% of aluminum and at least 15% of nickel, the steps consisting of heating the material to above 600 F. and subjecting it to a regulated cooling action. i

' 4. In the treatment of nickel-copperaluminum alloy containing less than 20% of aluminum and at least 15% of nickel, the steps consisting of heating the material to .between 600 F. and 1000 F. and subjecting it to regulated cooling.

5. In the treatment of' nickel-copperaluminum alloy containing at least 15% of nickel and less than 20% aluminum, the steps consisting of subjecting the material to a temperature between 1000 F. and 1200 F. and subjecting it to a regulated cooling.

6. In a the treatment of nickel-copperaluminum alloy containing less than 20% of aluminum and at least 15% of nickel, the

steps consisting of heating the material to between 1000"v it to cool.

7. In the treatment of nickel-copperaluminum alloy containing less than 20% of aluminum and at least 15% of nickel, the steps consisting of heating the material to between 1200 F. and 1500 F. and allowing ittocooL' KI 8. In the treatment of nickel-copper- F. and 1200 F. and allowing aluminum alloy containing less than 20% of aluminum and at least 15% of nickel, the

steps consisting of rapidly cooling 2. hard steps consisting of rapidly'cooling a hard alloy containing nickel, copper and aluminum to soften it, and then heating same at temperature between 600 F. and 1200 F. and slowly cooling same.

10. As a new art'cle of manufacture, an

alloy whose major constituents are nickel, copper and aluminum, one of the other metals being present to a greater percentage than the aluminum, the aluminum bemg less than 20% and the nickel being at least 15%, said alloy having a physical structure such asis produced by heat treating an alloy 0 ing it to cool.

11. As a new article of manufacture, an alloy whose major'constituents are nickel, copper and aluminum, one of the other metals bein present to a greater percentage than the a uminum, the aluminum being less than 20% and the nickel being at least 15%, said alloy having a physical structure such as is produced by heat treating an alloy of this composition to between 1000 and 1200 F. and allowing it to cool.

12. As a new article of manufacture, an alloy whose major constituents are nickel, copper and aluminum, one of the other metals being present the aluminum, the aluminum being less than 20% and the nickel being at least 15%, said alloy having a physical structure such as is produced by heat treating an alloy of this compositionv to "between 1200 and 1500 F. and allowing it to cool.

In testimony whereof my hand.

. WILLIAM A. MUDGE.

to a greater percentage than- I have hereunto set I f this composition to above 600 and allow-. 

